1. Field of the Invention
The invention relates to a portable device to move large items, such as pre-built walls, into, or out of, the vertical position.
2. Brief Description of the Prior Art
The construction of buildings with prefabricated wall sections is a common practice. The process of standing a stud wall begins with the construction of the stud wall on a horizontal surface such as a floor or a slab foundation. The stud wall includes top and bottom plates and a plurality of structural members, or studs, joining the top and bottom plates Such prefabricated wall sections, which may vary in length, generally are placed horizontally on the floor of the building structure. The edge that will ultimately become the lower edge of the horizontal wall section, is placed immediately adjacent the floor location on which it will rest in its vertical, upright position. The wall section is lifted and tilted into its desired vertical position, and the section is then secured to the sub-floor. Standing a stud wall typically requires a minimum of three workers to accomplish the task safely and easily. The stud wall is urged into a vertical position and held in place by two workers as a third worker secures the stud wall to other building structures.
The process works efficiently when the necessary manpower is present. However, with the trend toward do-it-yourself home building as well as the use of skeleton crews by commercial builders, the requisite minimum of three workers to stand a stud wall is not always available. When only two workers, such as a husband and wife building their own home, attempt to raise a stud wall the potential for serious injury is ever present.
Many devices such as mobile cranes, have been provided for use in lifting loads, including prefabricated walls. Mobile cranes are quite expensive and due to their weight and cumbersome nature, they are usually moved to a job site by the use of a trailer type vehicle. It has also been suggested to provide lifting devices, such as wall jacks, to raise the prefabricated wall sections from horizontal to final vertical position. Patents have issued disclosing a wall jack construction comprising a mechanical hoist having an elongated boom, the lower end of which is pivotally attached by a hinge to the floor of the building construction. Attached to a lower end portion of the boom is a winch with cable. The cable passes about a sheave on the upper end of the boom, and the outer end of the cable is suitable connected to the prefabricated wall adjacent its eventual upper end. The winch is manually operated to pivotally raise the wall section to a vertical position as the boom pivots from vertical to a generally 45 decree angular position during the lifting operation.
U.S. Pat. No. 5,322,404 provides a lifting device for raising prefabricated wall sections of a building from a horizontal to a vertical upright position during building construction.
U.S. Pat. No. 5,634,301 discloses a stud wall raising apparatus that permits a single user to raise a stud wall without assistance. The device has a T-shaped wall fixture, a fixed stud brace attached to the wall fixture by hinge means, a movable stud brace and a plurality of lock bars connecting the fixed and movable stud braces.
A need has been recognized in the art for a stud wall raising apparatus that allows a single individual to raise a stud wall so that the stud wall can be properly positioned and attached to other building structures. Such an apparatus must be simple to use, such that it can be operated by construction workers and lay persons alike. Furthermore, the device should be inexpensive to manufacture and durable when used in a commercial setting.